JP3579050B2 - Particularly, a method of axially fixing a shaft in a bearing case of a wiper device for cleaning a windshield of an automobile, and a wiper device - Google Patents

Description

The present invention particularly relates to a method of fixing a shaft in an axial direction in a bearing case of a wiper device for wiping a windshield of an automobile, and an annular groove is provided in a shaft portion projecting in an axial direction from the bearing case. Further, the present invention includes a drive mechanism and a link mechanism connected to the drive mechanism, and at least one of the drive mechanism and the link mechanism includes at least one rotation or swing shaft supported in the case. The shaft relates to a wiper device in which a shaft portion provided with an annular groove rises on at least one side from above the case.
German Patent Application (DE) 40 28 892 A1 describes a drive mechanism, in particular for a windshield wiper of a motor vehicle, which protrudes from one end of a bearing case and has a radial groove. The shaft. Furthermore, an annular gap is arranged between the shaft and the bearing case. Axial fixing of the shaft to the bearing case is provided by a resilient plastic bush that is rigidly mounted in the bearing case and inserted into the annular gap. In addition, the bush is provided with a radially inwardly projecting sealing flange which engages the annular groove of the shaft. This bush replaces the usual retaining ring or C-ring inserted into the annular groove to secure the shaft to the bearing case.
In the above drive mechanism, the inner hole of the bearing case, the diameter of the shaft, and the positional relationship of the shaft with respect to the bearing case need to be accurately adjusted to each other. With small play in the annular gap between them. If the play is too small, the bush cannot be inserted. If an excessively large play is formed, moisture may enter the shaft bearing from the outside and may be damaged. When the shaft is not coaxially arranged with respect to the bearing case, the bush cannot be inserted. To insert the bush, when the shaft is aligned under the action of force, the bush is inserted, then the force aligning the shaft is removed, a large pressure acts between the shaft and the bush, this pressure is Increases wear causing premature operation failure.
Accordingly, it is an object of the present invention to provide a method and a wiper device of the type described above, in which the shaft can be easily supported in the axial direction in the bearing case and the risk of premature failure is reduced.
In order to achieve the above object, according to the present invention, there is provided a method of fixing a shaft of a windshield wiper device so as to be immovable in an axial direction with respect to a bearing case. After the annular groove is formed, the shaft is inserted into the bearing case and positioned in the bearing case, and then, at least partially, a plasticized plastic material or metal is injection-molded around the annular groove. A method is provided.
Therefore, in the method of the present invention, after the shaft is inserted into the bearing case, the shaft portion rising on the bearing case is injection molded around with the plasticized and hardened material. This plasticized material can be either a plastic material or a metal. With this operation, the material penetrates into the annular groove of the shaft and is further placed on the front end of the bearing case. Thereby, the shaft is axially fixed to the bearing case. When the material is cured or permanently hardened, it acts as a bearing to support the shaft and prevents ingress of dust and moisture into the bearing from the periphery and leakage of lubricant from the bearing. Acts as a seal. The method of the present invention does not require that either the bore of the bearing case or the diameter of the shaft be manufactured with a high degree of accuracy to that dimension in order to form a precisely defined annular gap. Has the advantage that it is not necessary to align the shaft concentrically with respect to the bore of the bearing case. Further, in order to fix the shaft in the axial direction, it is not required that members such as a bush to be inserted or the like be extremely accurate. The manufacture of the shaft fixing means of the present invention is easy and quick. As will be apparent, generally, the shaft is aligned or centered after insertion into the bearing case. However, this operation is not always necessary. The injected material can also fix the shaft at an offset or inclined position in the bearing case. Another advantage of the method according to the invention is that the internal shape of the bearing case can also be conical. This is particularly beneficial in the case of cast casings. Furthermore, after the manufacture of the bearing case, there is no need for any post-treatment, especially for expanding the internal shape to a predetermined size. In particular, if the bearing case is made of aluminum die-castings, no mechanical after-treatment is required, despite the considerable dimensional tolerances due to the cooling of the bearing case.
The shaft is heated before injection molding, in particular to a temperature of 200 ° C. ± 30 ° C., in order to form a play between the shaft and the hardened plastic material or the hardened metal. After injection molding, the hardening or permanent hardening of the material takes place at a faster rate than the cooling of the shaft, and a certain play is formed by the amount of shrinkage of the shaft, thereby ensuring a light rotation of the shaft. If it is desired that the cooled material fit tightly into the shaft, the shaft can be cooled to a temperature below ambient or below operating temperature before the injection molding operation.
Advantageously, the plastic material or metal is injection-moulded on the shaft in at least one of the axial and radial directions. Depending on the shape and proximity of the shaft part, its length and whether plastic material or metal is used, this material is injected radially or pressed axially so that it is pressed on both sides. Is done. Axial injection is particularly useful when the shaft is not accessible or extremely difficult to access from the side.
In a further development, it is provided that different plastic materials or metals can be injected into this part simultaneously or sequentially. In this case, it is possible to use materials which are suitable for a low coefficient of friction, a good sealing effect and a high degree of resistance to certain substances such as grease, oil, water or aggressive agents. Through suitable supply openings, these materials can be injected onto the shaft part continuously or simultaneously. In this way, the characteristics of different materials can be combined.
In order to prevent the plastic material or metal injected into the shaft part from emerging from the mold space, the shaft part is at least partially enclosed and / or covered with a tool during the injection molding operation and the tool and the shaft part A hollow space is formed between them. This tool is beneficial in that it deflects the plasticized material around the front of the bearing case and secures it on the bearing case, preventing axial slip and circumferential rotation.
The fixing of the plastic material or metal on the bearing case can be beneficially effected by injecting the material into a recess arranged outside the axial end of the bearing case. These recesses can furthermore have undercuts and can be formed, in particular, in the form of dovetails. Thus, it is possible to further prevent dust and moisture from entering the bearing of the shaft.
The shaft is preferably fixed to the bearing case via another tool until the plastic material or metal is hardened or permanently hardened. This ensures that the axial play of the shaft in the bearing case does not exceed a predetermined amount.
In a further development, the sealing of the annular gap between the shaft and the bearing case takes place at least during the injection molding operation. This prevents intrusion of plastic material or metal into the annular gap. Furthermore, this sealing operation offers the possibility of holding the injection molded material around the shaft section under pressure until the material has hardened or permanently set. This further increases tightness.
Further, according to the present invention, a drive mechanism and a link mechanism connected to the drive mechanism are provided, and at least one of the drive mechanism and the link mechanism is provided with at least one rotation or swing shaft supported in a case. A windshield wiper device manufactured by the method described above, wherein the shaft portion provided with the annular groove of the shaft rises from the case on at least one side, wherein at least a part of the wiper device is provided around the annular groove. Further, there is provided a wiper device in which an injection-molded plastic material or metal forms a fixing member for fixing the shaft immovably in an axial direction with respect to a case.
The above-described advantages are obtained by the structure of the present invention.
Friction between the shaft and the plastic material or metal can be reduced in a beneficial manner, to which a lubricant is added. Such additions may be metal additives, plastics or liquid additives.
In a preferred embodiment, the shaft part has a plurality, in particular four, annular grooves. The advantage of this arrangement is that the annular grooves form a kind of labyrinth seal, which prevents the entry of dust and moisture into the shaft bearings to a very high degree. Further, the plurality of annular grooves evenly distributes the axial force acting on the shaft and is widely introduced into the material surrounding the annular grooves. Thus, damage to the axial bearings of the shaft due to axial force peaks is prevented.
Advantageously, the width of the annular grooves is greater than the gap between adjacent annular grooves. Accordingly, the width of the portions of material that engage the annular groove is also relatively large, which reduces the slack in these portions, especially at peak axial forces. This is particularly beneficial where plastic materials are used and where such relatively thick wall sections are formed.
Especially in the case of high-speed shafts, the fact that the annular groove has a rounded inner edge, i.e., a curved inner edge on the shaft side, causes a local temperature peak due to friction or a local temperature increase in the axial bearing. Is prevented. Thus, material penetrating into the annular groove is prevented from having sharp edges that can locally overheat.
Advantageously, material is prevented from penetrating into the annular gap between the shaft and the bearing case, which is sealed, for example, by a washer surrounding the shaft and mounted on the front side of the bearing case. .
The risk of damage to the axial bearing is advantageously prevented, and the injected plastics material or metal is inclined in particular conically towards the end of the shaft. Furthermore, since this tilting reduces the volume, the axial bearing has the advantage that there is less play with respect to the shaft circumference in the tilting region, which results in a better sealing effect.
The plastic material is preferably a thermoplastic or a thermoset plastic (duroplastic), in particular a polyamide such as polyamide 6/12, and the metal is preferably a copper, lead and / or tin alloy. When using a thermoplastic, the thermoplastic is plasticized by heating and injected around the shaft. Until the injected thermoplastic material or metal is cooled and hardened or permanently hardened, the wiper shaft is axially fixed to the bearing case by an auxiliary tool. If a thermosetting plastics material is used, the thermosetting plastic is activated, for example by the addition of a hardener, into a plastic state. This thermosetting plastic is cured particularly by applying heat, and fixes the shaft. The heating of the thermosetting plastic material can be performed, for example, by heating the shaft.
When the plastic material or metal is hardened or permanently hardened, it is beneficial in forming a shaft axial bearing and seal. As mentioned above, no other components are required for the operation of the bearing and seal.
Preferably, in the region of the axial end of the bearing case, outside the bearing case, a recess is provided which is injection-filled with a plastics material or metal injection-moulded around the annular groove. This changes the shape of the bearing case, which forms the fixing point of the material, so that this material is firmly connected to the bearing case and the shaft is firmly held axially by plastic material or metal.
Another way to achieve an optimal seal is to incorporate another seal, such as an O-ring, in the plastic material or metal. In this case, a material formed to have an optimum coefficient of sliding friction can be used as the plastic material. For example, an optimum sealing effect can be obtained by an O-ring that is injected, that is, integrated into the plastic material. . In this way, the properties of the O-ring can be combined with the properties of the plastic material.
In some embodiments, the shaft is provided as a drive shaft for a wiper motor. In another embodiment, the shaft is a wiper bearing shaft. In the embodiment in which the shaft is the drive shaft of the wiper motor, the bearing case is a case of the wiper motor or its gear. In the embodiment in which the shaft of the wiper bearing is used, the bearing case is formed of a bearing bush that receives the shaft.
Other advantages, features and details of the present invention will become apparent from the dependent claims and the following detailed description of preferred embodiments which refers to the accompanying drawings. here,
FIG. 1 is a side view of a wiper bearing,
FIG. 2 is an enlarged view of detail II of FIG. 1,
FIG. 3 is a view of a wiper shaft of the wiper bearing of FIG.
FIG. 1 shows a wiper bearing indicated by reference numeral 1 as a whole, and a wiper shaft 3 is fixed in a bearing case 2 so as to be able to rotate or swing. At the opposite end 5 of the knurled cone 4 of the wiper shaft 3, a crank 6 having a pressed-on ball pin 7 is arranged to transmit force or rocking movement. A washer 8 is inserted between the crank 6 and the lower front end of the bearing case 2. Through the washer 8, the play in the longitudinal direction of the wiper shaft 3 in the bearing case 2 can be adjusted to, for example, a maximum of 0.3 mm. The wiper shaft 3 is preferably axially supported by the washer 8 in a slightly elastic manner. Otherwise, the bearing case 2 has a fixing device 9 for fixing, for example, to the body of an automobile.
The wiper shaft 3 has a shaft portion 11 rising from the bearing case 2 above the upper front end portion 10, and the shaft portion is partially injection-molded with a plastic material 12 or metal. One or more washers 13 are interposed between the upper front end 10 and the plastic material 12. The wiper shaft 3 is fixed in the bearing case 2 in the axial direction via a plastic material 12 surrounding the shaft portion 11.
FIG. 2 shows an enlarged detail II of FIG. Here, it can be seen that four annular grooves 14 are arranged in the shaft part 11 in front and behind. The lower annular groove 14 is advantageously arranged flush with the surface of the upper washer 13. The plastic material 12 injected around the shaft portion 11 is arranged flush with the surface of the upper washer 13 and engages with the annular groove 14. The optimal fixing of the shaft part 11 in the plastic material 12 is achieved by the fact that these annular grooves have a large width with respect to their respective spacing. Therefore, the part of the plastic material 12 that engages with the annular groove 14 has a large width, and there is no risk of failure due to loosening, and an extremely large axial force is transmitted from the wiper shaft 3 to the plastic material 12. Can be.
FIG. 2 further shows that a washer 13 rests on the upper front end 10 of the bearing case 2 and that an annular gap is arranged between the bearing case 2 and the shaft 3. A bearing bush 16 supporting the wiper shaft 3 and the seal ring 17 is arranged in this annular gap.
FIG. 3 shows the wiper shaft 3 in FIG. 1 before being assembled in the bearing case 2. At the lower end of the wiper shaft 3 there is a receiving pivot 18 to which the crank 6 is riveted, for example. Furthermore, annular grooves 14 are visible in the upper shaft part 11, which project from the bearing case 2 when the wiper shaft 3 is assembled. Finally, a notched conical portion 4 and a thread 19 are shown for receiving and securing the securing member of the wiper arm.
The figure shows one embodiment of a wiper shaft 3 which is axially fixed in a bearing case 2 via a plastic material 12. However, the present invention is not limited to the illustrated embodiment, and the shaft of the drive mechanism and the axial fixing thereof are also included in the scope of the present invention.

Claims (19)

A method for fixing a shaft (3) of a windshield wiper device to a bearing case (2) so as not to be movable in an axial direction, wherein a portion (11) of the shaft (3) protruding from a bearing case in an axial direction. An annular groove (14) is formed in the shaft case (3), and the shaft (3) is inserted into the bearing case (2) and positioned in the bearing case (2). And injecting plasticized plastic material (12) or metal. The method according to claim 1, wherein the shaft is heated to a temperature of 200 ° C. ± 30 ° C. before the injection molding. Method according to claim 1 or 2, wherein the plastic material (12) or metal is injected onto the part (11) in at least one of an axial and a radial direction. Method according to one of the claims 1 to 3, characterized in that a plurality of plastic materials (12) or a metal is injected simultaneously or successively on the part (11). 5. The injection molding device according to claim 1, wherein said part is at least partially surrounded or covered by a tool, forming a hollow gap between said tool and said part. The method according to any one of the preceding claims. 6. The plastics material (12) or metal is injected at least partially around the axial end (10) of the bearing case (2). the method of. 7. The plastic material (12) or metal is injected into a recess located outside the axial end (10) of the bearing case ( 2 ). 8. The method described in. The shaft (3) is fixed to the bearing case (2) by another tool until the plastic material (12) or the metal is hardened or permanently hardened. The method described in one. 9. The method according to claim 1, wherein the annular gap (15) between the shaft (3) and the bearing case (2) is sealed at least during injection molding. A drive mechanism and a link mechanism coupled to the drive mechanism, at least one of the drive mechanism and the link mechanism being at least one rotating or swinging shaft (3) supported in a bearing case (2). 10. The method according to claim 1, wherein the shaft portion (11) provided with the annular groove (14) of the shaft (3) rises from the case (2) on at least one side. A windshield wiper device manufactured by the method described above, wherein an injection molded plastic material (12) or metal at least partially surrounds the annular groove (14) around the shaft (3). The wiper device is characterized in that a fixing means for fixing the movable member in the axial direction with respect to (1) is formed. 11. The wiper device according to claim 10, wherein the plastic material (12) or the metal contains a lubricant. The wiper device according to claim 10, wherein the shaft portion (11) has a plurality of annular grooves (14). 13. The wiper device according to claim 12, wherein a width of the annular groove (14) is larger than a gap between adjacent annular grooves. The annular gap (15) between the bearing case (2) and the shaft (3) is sealed by a washer (13) surrounding the shaft (3) and mounted on the front side of the bearing case (2). The wiper device according to any one of claims 10 to 13 , wherein: It injected plastic material (12) or outside of the metal wiper device according to any one of claims 10 to 14, characterized in that inclined toward the shaft end conically. 11. The method according to claim 10, wherein the plastic material (12) is a thermoplastic or thermosetting plastic material which is a polyamide, and wherein the metal comprises at least one of copper, lead and a tin alloy. 16. The wiper device according to any one of 15 . The plastic material (12) or metal, when hardened or permanently hardened, forms an axial bearing that axially supports the shaft (3) and a seal between the shaft and the bearing case. A wiper device according to any one of claims 10 to 16 . Sealing member is a wiper apparatus according to any one of the plastics material (12) or claim 10 to 17, characterized in that incorporated into the metal. It said shaft (3), the drive shaft of the wiper motor or the wiper device according to any one of claims 10, wherein 18 to be a shaft of the wiper bearing.

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